The present invention relates generally to medical devices and, more particularly, to hemostasis valves for use within percutaneous catheter introducers.
The use of catheter introducers in percutaneous medical procedures is well known in the art. A catheter introducer typically includes a long sheath having a first or proximal end positioned within a vein or artery of a patient and a second or distal end positioned immediately external to the epidermis of the patient. A lumen between the proximal and distal ends provides an access passageway for outside the body to the vein or artery lumen. Since the control of bleeding is obviously essential when such catheter introducers are utilized, conventional catheter introducers include a hemostasis valve assembly positioned at the proximal end of the sheath to permit a loader, catheter or other medical instrument to be introduced into the body of the patient through the sheath lumen while precluding blood from flowing out of the introducer.
In many percutaneous medical procedures, a small diameter guide wire is passed through the introducer sheath lumen and inserted into a vein or artery. The guide wire serves as a guide for a large diameter loader, catheter or other medical instrument employed later in the procedure. It is therefore necessary for the valve assembly to provide a sufficient seal around the small diameter guide wire to prevent excessive blood loss through the proximal end of the sheath. However, the valve assembly must also allow passage of, and sealingly engage, the large diameter loader, catheter, or other medical instrument, so as to prevent the flow of blood through the introducer.
One type of valve commonly used to control the flow of blood is referred to as a xe2x80x9cduckbillxe2x80x9d valve. A conventional duckbill valve includes a pair of walls, each having a generally planar configuration, which converge in the distal direction toward the patient and coapt or meet along a line or slit. In the absence of any instrument passed through the duckbill valve, the surrounding fluid exerts radial pressure on the convergent walls of the valve to help keep the slit closed. When an instrument such as a guidewire or catheter is inserted into a conventional duckbill valve, it passes between the converging walls of the valve and through the slit. This causes the walls to separate and to create an undesirable flow channel between the slit and the instrument, where the slit on either side of the instrument is slightly distended in a manner that resembles the corner of the eye. Therefore, duckbill valves are typically used in combination with another sealing member to prevent leakage.
U.S. Pat. No. 4,929,235 discloses a catheter introducer valve assembly designed to overcome the limitations of the prior art duckbill valves. The valve assembly includes a first valve having a Y-shaped slit which seals off any flow of blood from the sheath of the introducer during the time a catheter tube is not present. The first valve thus performs a function similar to that of a duckbill valve. A second valve, typically a disc seal with a small through-hole, seals around the catheter tube during and after the insertion of the catheter tube into the introducer so as to seal off any flow of blood.
Prior art catheter introducer valve assemblies have been successful in accomplishing the primary purpose of shutting off the flow of blood in the sheath when no medical instrument is present therein, and have been effective in allowing passage of and sealingly engaging the outer diameter of a catheter or other medical instrument, but have been unable to provide adequate seals around both a small diameter guide wire and a large diameter medical instrument passing through the introducer. The prior art valve assemblies typically include a seal which is adapted to sealingly engage around the relatively large diameter medical instrument such that no seal is formed around a relatively small diameter guide wire. With further reference to U.S. Pat. No. 4,929,235, the through-hole of the second valve has a diameter adapted to sealingly engage a catheter or loader having a diameter typically of approximately 0.3 inches. A typical guide wire has a diameter of approximately 0.035 inches such that once the catheter or loader has been removed, leaving the guide wire alone within the valve assembly, a substantial gap exists between the second valve and the guide wire whereby blood may pass through the introducer. Moreover, even the presence of a duckbill valve does not eliminate leakage around the guidewire because of the corner of the eye problem noted above.
Accordingly, there is a need for a catheter introducer valve assembly which provides for the effective sealing of blood flow during three separate and distinct conditions: when no medical instrument is inserted through the assembly, when a relatively large diameter medical instrument is inserted through the valve assembly, and when a relatively small diameter guide wire is inserted through the valve assembly. In addition, there is a need for a guide wire seal which provides an effective seal around the exterior of a guide wire which alone has been inserted through the valve assembly, but which also provides for the easy passage of a relatively large diameter catheter or loader.
The present invention provides a hemostasis valve assembly adapted for use within a catheter introducer. In a first mode of operation, the valve assembly seals blood from flowing through the catheter introducer when no instrument or device is passing therethrough. In a second mode of operation, the valve assembly seals around a relatively small diameter guide wire, while in a third mode of operation the valve assembly seals around a relatively large diameter elongated member or catheter. The valve assembly consistently and continuously seals off the flow of blood during all three modes of operation.
In accordance with one exemplary embodiment of the invention, a duckbill-type hemostasis valve for use in catheter introducer is provided. The valve has a valve body with a proximal end and a distal end, the valve body being sized to be received within a catheter introducer and being made of an elastomeric material. A slit opening in the valve body remains closed in the absence of a medical instrument passed through the introducer. The valve body includes an annular flange on the proximal end thereof defining on its exterior at least one sealing surface adapted to engage a complementary surface on the catheter introducer and prevent fluid flow therebetween. The annular flange circumscribes a proximal opening formed in the valve body and defines a central axis for the valve body. A pair of distally extending side walls connect to the annular flange and are opposed diametrically across the central axis. A pair of distally extending duckbill walls connect to the annular flange and are opposed diametrically across the central axis. The duckbill walls each extend between the two side walls and converge toward each other in the distal direction, wherein the distal end of the valve body is defined by the distal ends of the side walls and the duckbill walls.
The slit opening is formed in the distal end of the valve body and includes a middle segment that forms a separating line between the pair of duckbill walls. The slit opening further includes a pair of side segments disposed on either end of and generally perpendicular to the middle segment, the slit opening thus defining an H-shape and the distal ends of the side walls and the duckbill walls being joined together in a continuous manner surrounding the H-shaped slit opening.
Optionally, at least one reinforcing rib is provided on each duckbill wall that extends generally in a plane parallel to the central axis and biases the opposed duckbill walls toward each other. The reinforcing ribs provided on each duckbill wall may lie in a plane that includes the central axis. Desirably, there are multiple reinforcing ribs provided on each duckbill wall, and more preferably there are three reinforcing ribs provided on each duckbill wall, a middle one of which lies in a plane that includes the central axis. The middle reinforcing rib is thicker than the others.
The duckbill walls may be generally planar, or may be concavely curved with respect to the exterior of the valve body. The side walls are desirably curved generally about the central axis. Preferably, the middle segment of the slit opening is linear, while the side segments of the slit opening are curved and generally centered about the central axis.
In accordance with another embodiment of the invention, a duckbill-type hemostasis valve for use in catheter introducer comprises a valve body having a proximal end and a distal end, the valve body being sized to be received within a catheter introducer and being made of an elastomeric material. A slit opening remains closed in the absence of a medical instrument passed through the introducer. The valve body defines a central axis and, on its exterior, at least one sealing surface adapted to engage a complementary surface on the catheter introducer and prevent fluid flow therebetween. A pair of distally extending side walls are diametrically opposed across the central axis, and a pair of distally extending duckbill walls connected to the side walls are diametrically opposed across the central axis, the duckbill walls each extending between the two side walls and converging toward each other in the distal direction. The distal end of the valve body is defined by the distal ends of the side walls and the duckbill walls.
At least one reinforcing rib provided on each duckbill wall extends generally in a plane parallel to the central axis and biases the opposed duckbill walls toward each other. The slit opening is formed in the distal end of the valve body and includes a middle segment that forms a separating line between the pair of duckbill walls. The slit opening further includes a pair of side segments disposed on either end of and generally perpendicular to the middle segment, the slit opening thus defining an H-shape and the distal ends of the side walls and the duckbill walls being joined together in a continuous manner surrounding the H-shaped slit opening